How data centre networking is evolving to meet the demands of virtualisation

By Jon Toor, VP of marketing, Xsigo.

Date: 9 Jan 2012

Ethernet switching is in a sea change, and server virtualisation is a big part of the reason why. Gartner recently published a new competitive landscape for data centre Ethernet switches. In that report, titled “Competitive Landscape: Data Centre Ethernet Switches, Worldwide, 2011,” the authors made several interesting comments about this evolving space and how trends such as virtualisation and cloud computing have created the need for next-generation fabric-based solutions that provide far more agility and performance.

This report features a number of vendors including Brocade, Extreme Networks, Juniper Systems and Xsigo in a group that Gartner calls “Data Centre Network Specialists.” The definition of this group is vendors that “depend on their dedicated focus and specialisation in networking to innovate and meet the fast-evolving needs of customers.” The words “fast evolving” nicely sum up what’s going on.

In the past, there was no clear distinction between the switches found in a data centre and those used elsewhere in the organisation. But this is now changing. Because a cloud data centre behaves as a sort of compute fabric – where any server can run any application – the infrastructure must behave that way as well. For that reason, the data centre Ethernet switch is taking on a new look. Gartner characterised this ongoing transition as “an important step in the evolution from box-centric, data-centre-optimised Ethernet solutions to a fabric-based approach for large data centre and cloud infrastructure.”

In a narrow view, you could say that actually very little has changed in the switching space. Applications still need access to specific resources: networks, storage and the devices that surround them, such as load balancers, security devices, and other appliances. And those applications still require sufficient bandwidth to ensure that performance meets the objectives.

The difference with virtualisation is this: those exact same requirements must now be met in a dynamic world, where multiple applications could reside on any server, not just one application on a dedicated device. This is a big change, making switching requirements both more dynamic and more I/O-intensive.

Here are three examples of the issues this creates for the switching infrastructure:

• The “East-West” problem: It used to be that data centres were laid out in nice, orderly tiers, allowing data to flow in predictable paths. But with virtualisation, applications can run anywhere. This creates messy server-to-server data paths where data must negotiate multiple layers of infrastructure to reach its destination. The resulting latencies, bottlenecks and general bad behaviour are called the “East-West Problem.” If we’re going to virtualise more and make data centres truly resemble a cloud, this must be addressed.

• Exponential performance demands: Virtualised servers demand a lot more I/O bandwidth than bare metal servers do. While most of the industry has experienced a somewhat leisurely transition from 1Gb to 10Gb connections, hard-core virtualisation users have hungrily jumped to the highest available speeds, namely 10Gb, 20Gb or 40Gb. They have simply found that virtualisation works better with more bandwidth.

• VLAN Exhaustion: VLANs did a great job of addressing the problem they were created to solve. But when it comes to creating large numbers of isolated interconnects within an agile data centre, they don’t scale well. You can run out of VLANs. Or they can become a management nightmare to administer. Eliminating this problem — while providing the needed isolated connections — is a challenge that must be overcome.

Gartner stated in the report that, “data centre switching is a fast-evolving market with a different problem set and several new technologies likely to disrupt legacies.” This is happening already and the key to success is to meet the most important requirement of all: to provide a seamless, non-disruptive path forward towards a more efficient, lower-cost data centre.